Dies and presses that compact powdered materials into solid briquettes are in widespread use. Such manufacturing techniques are now commonplace and are used to create a wide variety of products from complex metal machine parts to pharmaceutical tablets. A problem of powder compacting in certain technical areas such as for use in X-ray analysis involves creating a uniformly dense briquette. If a powdered material is not properly compacted, the final compacted briquette has areas that vary in density. The uneven density results in a briquette that provides improper readings dependent upon position of the briquette in the analysis equipment. Uneven density also can cause the briquette to break prematurely under stress.
Another similar problem with the manufacture of briquettes, originates from the presses used to compact the powdered materials. Until recently, briquette presses had no operating controls to regulate the force the press applied to the briquette during a compression cycle. The result was a large variation in density from one briquette to another. Eventually, control systems have been developed that measure and regulate the peak pressures applied by a press during a compression cycle. Exemplary embodiments of such control systems are shown in U.S. Pat. Nos. 4,946,634 to Shaner, 4,863,651 to Koten, 4,651,273 to Braitinger et al. and 4,413,967 to Burry. These systems resulted in a greater consistency in the density of briquettes produced from the same press.
Many different types of powdered materials are compacted by briquette presses. All material has some elasticity when compressed. Consequently, when powder material is compressed into a briquette, the briquette often expands when released from the press. The sudden expansion of the briquette may cause the briquette to develop stress cracks and flaws that affect its overall strength and surface integrity. To avoid such expansion stresses, briquette presses must slowly decompress the briquette until it reaches ambient pressure. Since the rate of decompression varies as a function of the compression force, size of the briquette, and composition of the briquette, decompression calculations are difficult to utilize during manufacturing. Since most powder compacted materials are used either to create parts that are not subject to major stresses or are sintered in a second operation, manufacturers ignore the decompression stresses and their effect on the quality of the briquette. Often, to maximize productivity, compacted samples are ejected from the mold as soon as they are formed. Such manufacturing techniques maximize the decompression stresses and are the standard method of manufacturing where the defects caused by decompression stresses can be ignored. However, in such precise applications as X-ray spectrochemical analysis, decompression stresses on a compacted sample can vary both the results and quality of any analysis and cannot be ignored.
To conduct a statistically sound X-ray spectrochemical analysis for a material, many briquettes must be formed and tested. As such, it is desirable to automate the briquette press as much as possible without jeopardizing the quality of the formed briquette. Automating press operations is not a new concept. Examples of briquette presses that embody automated sample loading and ejection features are shown in U.S. Pat. Nos. 2,110,972 to Dinzil and 2,384,163 to Flowers. However, for the production of X-ray spectrochemical analysis, often the precision of the sample to be compacted cannot be efficiently achieved by automated means. Consequently, a custom automated system needs to be developed that automates the press to the highest degree possible, yet allow exact amount of powder material samples to be added by hand.
It is therefore an object of the present invention to create a briquette press, for forming X-ray spectrochemical analysis samples, that has a selectively programmable compression and decompression cycle, to efficiently produce high quality, uniform samples free of decompression stresses and associated methods for forming high quality briquettes.